Louis van Gaal's strategic decisions have let Man United down this season

Ryan Giggs might officially be Manchester United's assistant manager but, during games, Louis van Gaal's closest confidante appears to be a tactics board, which sits atop his lap with magnets symbolising United's players and the positions of their opponents.

This type of chalkboard is perfectly common in the coaching world, but it's rare for a manager to use it so intently during matches. Van Gaal rarely stands up and instructs his players and, despite being a fiery character, is seldom seen quarrelling with the fourth official either. The manager's concentration is firmly on the tactics.

Van Gaal's coaching style is that he's a tactician, who places a huge emphasis upon shape and positioning, on individual battles across the pitch, on who's marking whom, and who is in space.

It's a huge contrast from his opponent on Sunday, Arsene Wenger, who simply spectates and takes mental notes. It suggests that Van Gaal is constantly evaluating the situation, forever searching to give his side the initiative. But what exactly is the Dutchman spotting, analysing and then changing?

In Van Gaal's previous coaching job with the Netherlands, his tactical decisions were obvious. He settled on a three-man defence shortly before the 2014 World Cup, but nevertheless changed the system constantly; particularly in the knockout phase, where he used a 3-4-1-2 against Mexico, a 3-4-3 against Costa Rica and then a 3-5-2 in the semifinal against Argentina, with the midfield flipped from the Mexico game. His approach was, in general, to match the opposition in the centre of the pitch and to retain a spare man at the back.

More crucially, however, his tactical switches directly changed matches. The 3-4-1-2 against Mexico was abandoned in favour of a 4-2-1-3, with the Dutch wingers pushing back the opposition wing-backs and the full-backs storming forward to create two-versus-one situations down the flanks, which eventually resulted in Van Gaal's side turning the game.

At Manchester United, it has been a different story. There's a huge contradiction at the heart of Van Gaal's approach; he's constantly assessing the teams on his chalkboard and yet Man United's players are widely understood to be frustrated with their manager's stubborn insistence upon his "philosophy."

It's entirely possible to preach yet still adjust according to the demands of the opponent -- Pep Guardiola is a fine example of someone who does just that -- but when has Van Gaal's tactical decision-making unquestionably had a positive impact? It's easier to recall when he's got things wrong.

The most obvious example was in the reverse fixture against Arsenal, on a sunny Sunday afternoon in early October. Wenger's side triumphed 3-0, with the scoring finished within 20 minutes of kickoff. It was a brilliant performance from the Gunners, but owed much to disastrous tactics from Van Gaal.

United's manager was determined to dominate possession -- a tricky task at the Emirates -- and therefore used Bastian Schweinsteiger and Michael Carrick as the two deep midfielders in his 4-2-3-1 system, with Wayne Rooney as the No. 10. But dominating possession isn't simply about retaining the ball, it's also about winning the ball quickly.

Therefore, Van Gaal asked his players to press in midfield. However, asking that of two 30-somethings and 29-year-old Rooney -- none of them are famed for their mobility -- was a huge mistake against this Arsenal side.

Rooney would close down Francis Coquelin or Santi Cazorla in midfield, but then Schweinsteiger had to advance 25 yards to shut down the other. By the time he'd got there, it was too late, Arsenal had transferred the ball onto another player, usually into the space the German was meant to be patrolling. It left Carrick exposed to Mesut Ozil and Alexis Sanchez and Arsenal were rampant.

The approach made no sense. Van Gaal could have switched shape slightly to 4-1-4-1 to allow a more natural press. He could have used Morgan Schneiderlin, a more energetic player, who would help to press more effectively. Or he could have abandoned the press altogether. But this was the most disjointed strategy you'll see all season in the Premier League; everything was entirely out of sync.

That was an unusual game for Manchester United this season, because Van Gaal felt he needed to try something specific to control the midfield zone. This isn't generally an issue: inferior opponents are happy to sit deep and allow United time in midfield, confident their passing will be too slow and unambitious to offer regular penetration. They've often been right.

A fast start saw Arsenal coast to victory the last time they played Manchester United.

It's also difficult to judge how well Van Gaal's tactics have fared in truly big Premier League games, simply because United haven't had many of them this season. The peculiar nature of the league table means few of United's fixtures have been against obvious top-quality opposition. They've played the four sides above them in the league only one time apiece so far.

As well as the aforementioned game against Arsenal, United played Tottenham on the season's opening day, before it became clear Mauricio Pochettino's side were title challengers, and it was also impossible to judge whether Van Gaal was trying anything particularly unusual at that point. United were fortunate to win 1-0, courtesy of an own goal.

They faced Manchester City in October, when Van Gaal named a defensive-minded side. His 4-2-3-1 has often featured a deep-lying forward behind the main striker, but for that game he selected three central midfielders: Schweinsteiger, Schneiderlin and Ander Herrera. United dominated possession, but the game was a hopelessly dull 0-0.

United travelled to Leicester in November, when Van Gaal switched to a 3-4-1-2 to counter the strengths of the opposition. "I had to close the channels for [Jamie] Vardy and [Shinji] Okazaki, and we also had one man more in midfield so we had a lot of space and, because of that, we dominated the game," he said. United shut out Vardy in open play but were exposed on a counter-attack from one of their own corners. They drew 1-1.

Tactical acumen is most obvious in these big games against sides of roughly equal quality, but Van Gaal has made few impressive strategic decisions, either ahead of games or during. That must change quickly, starting on Sunday, or else that tactics board will start to look superfluous.

Michael Cox is the editor of zonalmarking.net and a contributor to ESPN FC. Follow him on Twitter @Zonal_Marking.